Weather World
City of Alton, Illinois
Alton Monthly Climate Averages
January |
February |
March |
April |
May |
June |
July |
August |
September |
October |
November |
December |
| Hi 37°F Lo 24°F | Hi 42°F Lo 27°F | Hi 54°F Lo 38°F | Hi 64°F Lo 46°F | Hi 74°F Lo 57°F | Hi 83°F Lo 66°F | Hi 86°F Lo 69°F | Hi 85°F Lo 67°F | Hi 80°F Lo 61°F | Hi 67°F Lo 50°F | Hi 54°F Lo 38°F | Hi 43°F Lo 31°F |
| 9 mph | 9 mph | 10 mph | 9 mph | 8 mph | 7 mph | 6 mph | 6 mph | 7 mph | 9 mph | 9 mph | 9 mph |
| 2.7 in | 2.8 in | 4.2 in | 5.4 in | 5.8 in | 4.5 in | 4.2 in | 4.3 in | 3.4 in | 3.6 in | 3.1 in | 3 in |
| 76% | 76% | 74% | 75% | 78% | 76% | 78% | 76% | 71% | 68% | 70% | 75% |
| 52% | 50% | 48% | 44% | 40% | 30% | 31% | 29% | 28% | 34% | 37% | 48% |
| 30.1 in | 30.1 in | 30.1 in | 29.9 in | 30.0 in | 29.9 in | 30.0 in | 30.0 in | 30.0 in | 30.0 in | 30.1 in | 30.1 in |
| 21 | 19 | 23 | 22 | 21 | 21 | 22 | 23 | 25 | 24 | 24 | 23 |
| 6 | 6 | 7 | 8 | 10 | 9 | 9 | 8 | 5 | 7 | 5 | 7 |
| 4 | 3 | 1 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 1 | 1 |
| 1 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 1 | 0 | 1 | 1 |
| 2 | 2 | 3 | 4 | 5 | 6 | 6 | 5 | 5 | 3 | 2 | 1 |
| 150 | 144 | 157 | 168 | 192 | 236 | 238 | 244 | 242 | 215 | 209 | 165 |
January |
February |
March |
April |
May |
June |
July |
August |
September |
October |
November |
December |
| Hi 3°C Lo -5°C | Hi 5°C Lo -3°C | Hi 12°C Lo 3°C | Hi 18°C Lo 8°C | Hi 23°C Lo 14°C | Hi 29°C Lo 19°C | Hi 30°C Lo 21°C | Hi 29°C Lo 20°C | Hi 27°C Lo 16°C | Hi 19°C Lo 10°C | Hi 12°C Lo 3°C | Hi 6°C Lo -1°C |
| 15 km/h | 15 km/h | 15 km/h | 15 km/h | 13 km/h | 11 km/h | 9 km/h | 10 km/h | 11 km/h | 14 km/h | 14 km/h | 15 km/h |
| 68 mm | 71 mm | 106 mm | 137 mm | 147 mm | 113 mm | 105 mm | 110 mm | 87 mm | 92 mm | 79 mm | 75 mm |
| 76% | 76% | 74% | 75% | 78% | 76% | 78% | 76% | 71% | 68% | 70% | 75% |
| 52% | 50% | 48% | 44% | 40% | 30% | 31% | 29% | 28% | 34% | 37% | 48% |
| 1021 mb | 1020 mb | 1018 mb | 1014 mb | 1014 mb | 1013 mb | 1015 mb | 1015 mb | 1016 mb | 1017 mb | 1020 mb | 1020 mb |
| 21 | 19 | 23 | 22 | 21 | 21 | 22 | 23 | 25 | 24 | 24 | 23 |
| 6 | 6 | 7 | 8 | 10 | 9 | 9 | 8 | 5 | 7 | 5 | 7 |
| 4 | 3 | 1 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 1 | 1 |
| 1 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 1 | 0 | 1 | 1 |
| 2 | 2 | 3 | 4 | 5 | 6 | 6 | 5 | 5 | 3 | 2 | 1 |
| 150 | 144 | 157 | 168 | 192 | 236 | 238 | 244 | 242 | 215 | 209 | 165 |
| Month |
| Avg. Temperatures |
| Avg. Wind Speed |
| Avg. Precipitation |
| Average Humidity |
| Avg. Cloud Cover |
| Pressure Average |
| Average Dry Days |
| Avg. Precip. Days |
| Avg. Snow Days |
| Average Fog Days |
| Average UV Index |
| Avg. Hours of Sun |
Averages are based on historical weather data from the past 10 years.